Using a Virtual Internet Protocol Address to Represent Dually Connected Hosts in an Internet Protocol Overlay Network

1. A method comprising: at a first router device in a network, receiving a packet from a first host device that is destined for a second host device in the network; determining that the packet is received on a first physical port associated with a virtual port and the virtual port being mapped to a plurality of physical ports of router devices in the network including the first physical port of the first router device and a second physical port of a second router device, wherein the virtual port has a Layer 3 address commonly shared by the plurality of physical ports; encapsulating the packet received from the first host device with an overlay header to generate an encapsulated packet that includes the Layer 3 address associated with the virtual port as a source address of the encapsulated packet and a Layer 2 address associated with the first host device; and sending the encapsulated packet to a third router device that is connected to the second host device to enable the third router device to determine, based on the Layer 2 address, that the first host device is reachable through the Layer 3 address of the virtual port.

2. The method of claim 1 , further comprising sending to the second router device a message indicating that the first host device is connected to the second router device and that the second router device can ignore learning the Layer 3 address when the second router device receives the encapsulated packet.

3. The method of claim 2 , wherein the message further indicates to the second router device that the first host device is accessible by the second router device via a local link between the second router device and the first host device.

4. The method of claim 1 , wherein encapsulating comprises encapsulating the packet with an Internet Protocol overlay header that comprises an Internet Protocol address assigned to the first host device.

5. The method of claim 1 , further comprising assigning an Internet Protocol (IP) address to the first host device before encapsulating the packet with the overlay header and the assigned Internet Protocol address is obtained from a database of Internet Protocol addresses, wherein the database is local to the first router device and the second router device.

6. The method of claim 1 , further comprising: receiving a response packet from the second host device; and storing Layer 2 address information and Layer 3 address information associated with the second host device.

7. The method of claim 1 , wherein sending the encapsulated packet to the third router device comprises sending the encapsulated packet to the third router device via a best available path in the network.

8. An apparatus comprising: a plurality of ports configured to send and receive communications over a network; and a processor configured to: receive a packet from a first host device that is destined for a second host device in the network; determine that the packet is received on a first physical port associated with a virtual port and the virtual port being mapped to a plurality of physical ports of router devices in the network including the first physical port of the first router device and a second physical port of a second router device, wherein the virtual port has a Layer 3 address commonly shared by the plurality of physical ports; encapsulate the packet received from the first host device with an overlay header to generate an encapsulated packet that includes the Layer 3 address associated with the virtual port as a source address of the encapsulated packet and a Layer 2 address associated with the first host device; and send the encapsulated packet to a third router device that is connected to the second host device to enable the third router device to determine, based on the Layer 2 address, that the first host device is reachable through the Layer 3 address of the virtual port.

9. The apparatus of claim 8 , wherein the processor is further configured to generate and send to the second router device a message indicating that the first host device is connected to the second router device and that the second router device can ignore learning the Layer 3 address when the second router device receives the encapsulated packet.

10. The apparatus of claim 9 , wherein the message further indicates to the second router device that the first host device is accessible by the second router device via a local link between the second router device and the first host device.

11. The apparatus of claim 8 , wherein the processor is further configured to encapsulate the packet with an Internet Protocol overlay header that comprises an Internet Protocol address assigned to the first host device.

12. The apparatus of claim 8 , wherein the processor is further configured to assign an Internet Protocol address obtained from a database of Internet Protocol addresses to the first host device before encapsulating the packet with the overlay header, wherein the database is local to the first router device and the second router device.

13. The apparatus of claim 8 , wherein the processor is further configured to: receive a response packet from the second host device; and store Layer 2 address information and Layer 3 address information associated with the second host device.

14. The apparatus of claim 8 , wherein the processor is further configured to send the encapsulated packet to the third router device via a best available path in the network.

15. A non-transitory computer-readable storage media encoded with software comprising computer executable instructions and when the software is executed operable to: receive a packet from a first host device that is destined for a second host device in the network; determine that the packet is received on a first physical port associated with a virtual port and the virtual port being mapped to a plurality of physical ports of router devices in the network including the first physical port of the first router device and a second physical port of a second router device, wherein the virtual port has a Layer 3 address commonly shared by the plurality of physical ports; encapsulate the packet received from the first host device with an overlay header to generate an encapsulated packet that includes the Layer 3 address associated with the virtual port as a source address of the encapsulated packet and a Layer 2 address associated with the first host device; and send the encapsulated packet to a third router device that is connected to the second host device to enable the third router device to determine, based on the Layer 2 address, that the first host device is reachable through the Layer 3 address of the virtual port.

16. The non-transitory computer-readable storage media of claim 15 , further comprising instructions operable to generate and send to the second router device a message indicating that the first host device is connected to the second router device and that the second router device can ignore learning the Layer 3 address when the second router device receives the encapsulated packet.

17. The non-transitory computer-readable storage media of claim 16 , wherein the message further indicates to the second router device that the first host device is accessible by the second router device via a local link between the second router device and the first host device.

18. The non-transitory computer-readable storage media of claim 15 , wherein the instructions operable to encapsulate comprise instructions operable to: assign an Internet Protocol address obtained from a database of Internet Protocol addresses to the first host device before encapsulating the packet with the overlay header, wherein the database is local to the first router device and the second router device; and encapsulate the packet with an Internet Protocol overlay header that comprises the Internet Protocol address assigned to the first host device.

19. The non-transitory computer-readable storage media of claim 15 , further comprising instructions operable to: receive a response packet from the second host device; and store Layer 2 address information and Layer 3 address information associated with the second host device.

20. The non-transitory computer-readable storage media of claim 15 , wherein the instructions operable to send the encapsulated packet comprise instructions operable to: send the encapsulated packet to the third router device via a best available path in the network.